The present invention relates to power steering devices for wheeled vehicles, and more particularly to a power steering device of the type which includes a steering shaft assembly, a driven member for operative connection with the steering road wheels of the vehicle and moved by rotational torque of the shaft assembly, an hydraulic cylinder for actuating the driven member by fluid under pressure supplied thereto from a source of fluid pressure, an hydraulic circuit connecting the cylinder to the fluid pressure the source, and valve means having a valve member to be moved in response to rotation of the shaft assembly in an axial direction, the valve means being disposed within the hydraulic circuit to control the supply of fluid under pressure in response to axial movement of the valve member.